JP2009159445A - COMMUNICATION DEVICE, COMMUNICATION SYSTEM, AND COMMUNICATION CONTROL METHOD - Google Patents

Abstract

A technique for providing a more effective diversity effect that is not affected by a distance between transmitting antennas or a multi-user environment without introducing delayed transmission is provided.
Another communication apparatus (200) using a communication frame having a frequency axis and a time axis.
) And the communication apparatus (100) that communicates between the communication apparatus and its own apparatus, the data allocation unit (140) that allocates data to be transmitted to the communication frame, and the frequency axis direction of data and / or for each of the communication frames A control unit (110) that controls the data allocation unit to change the allocation state in the time axis direction, and a transmission unit (130) that transmits a plurality of communication frames whose allocation state has been changed to other communication devices. It is characterized by that.
[Selection] Figure 1

Description

  The present invention relates to a communication device, a communication system, and a communication control method.

  Conventionally, in wireless communication, many transmission diversity techniques have been developed to reduce the harmful effects of fading. One of the simplest transmit diversity techniques is a delay diversity technique in which the same signal is transmitted from multiple antennas with different delays. This enhances the frequency selectivity from each transmit antenna to each receive antenna, thus providing an input channel equivalent with enhanced frequency diversity. In OFDM (Orthogonal Frequency Division Multiplexing), the frequency diversity captured by the transmitter can be used by an error correction decoder located in the receiver.

For example, as a first conventional technique using delay diversity, there is a technique (see Patent Document 1) that achieves a desired transmission rate without disposing a plurality of transmission antennas apart from each other. In addition, as a second conventional technique using delay diversity, there is a technique (see Patent Document 2) aimed at strengthening particularly in a multiuser scenario.
JP 2004-64654 A Special table 2007-515829

  In various propagation environments such as multipath and cell fringing, frequency selective fading countermeasures using delay diversity in the same frame may have a high correlation of fading, and all situations in dynamic environments. Can not cope with. Longer guard intervals are required by introducing additional delays in multi-carrier transmission systems that are often needed to achieve time (delay) diversity. Thereby, band efficiency falls. Furthermore, when the guard interval is not sufficiently long, mutual interference between carriers may occur.

  In view of this point, the present invention has an object to provide a technique (apparatus, method, system) that provides a more effective diversity effect that is not affected by the distance between transmitting antennas or a multiuser environment without introducing delayed transmission. To do.

In order to solve the above-described problems, the communication device according to the first invention provides:
A communication device (transmission device) that communicates between another device and its own device using a communication frame having a frequency axis and a time axis,
A data allocation unit that allocates data to be transmitted (encoding information (information symbols), redundancy information, etc.) to the communication frame;
A control unit that controls the data allocation unit to change the allocation state of the data in the frequency axis direction and / or the time axis direction for each of the communication frames;
A transmission unit for transmitting a plurality of communication frames whose allocation state has been changed to the other communication device;
It is characterized by having.

The communication device according to the second invention is
The control unit is
Controlling the data allocation unit to change the allocation state in the frequency axis direction of data to be transmitted (encoding information, redundancy information, etc.) for each communication frame;
It is characterized by that.

The communication device according to the second invention is
The control unit is
Controlling the data allocation unit to change the allocation state in the frequency axis direction and time axis direction of data to be transmitted (encoding information, redundancy information, etc.) for each communication frame;
It is characterized by that.

A communication device according to a fourth invention is
The assigning unit
The same data to be transmitted is assigned to a plurality of communication frames (that is, time diversity is performed).

A communication device according to a fifth invention is
The communication frame is OFDM-modulated and MIMO-multiplexed.

A communication device according to a sixth invention is
The communication frame is OFDM-modulated, MIMO-multiplexed, and space-division multiplexed.

A communication system according to a seventh invention is
A communication system that communicates between the communication device and another communication device using a communication frame having a frequency axis and a time axis,
The other communication device is
A receiving unit for receiving the plurality of communication frames transmitted from the communication device;
A signal processor that processes the plurality of communication frames received by the receiver based on the allocation state;
It is characterized by having.

The communication device according to the eighth invention is
A communication device (receiving device) that communicates between another device and its own device using a communication frame having a frequency axis and a time axis,
A plurality of communication frames, which are transmitted from the other communication apparatuses and to be transmitted (encoded information (information symbols), redundancy information (parity), etc.) are allocated in the frequency axis direction and / or the time axis direction. A receiving unit for receiving;
The allocation state when data (encoding information (information symbol), redundancy information, etc.) to be transmitted is allocated to the communication frame in the frequency axis direction and / or the time axis direction in the other communication device is acquired. An acquisition unit;
A signal processing unit that processes the plurality of communication frames received by the receiving unit based on the allocation state acquired by the acquiring unit;
It is characterized by having.

  As described above, the solution of the present invention has been described as an apparatus or a system. However, the present invention can also be realized as a method, a program, and a storage medium that records the program substantially corresponding to these. It should be understood that these ranges are also included. Each step of the method below uses an arithmetic processing unit such as a CPU or DSP as needed for data processing. The input data, processed / generated data, etc. are stored on magnetic tape, HDD. And stored in a storage device such as a memory.

For example, the method according to the ninth aspect of the present invention, which is realized as a method,
A communication control method in a communication device that communicates between another device and its own device using a communication frame having a frequency axis and a time axis,
A data allocation step for allocating data to be transmitted (encoded information (information symbols), redundancy information, etc.) to the communication frame;
A control step for controlling the allocation state of the data in the frequency axis direction and / or the time axis direction for each of the communication frames;
A transmission step of transmitting a plurality of communication frames whose allocation state has been changed to the other communication device;
It is characterized by having.

  According to the present invention, it is possible to provide a more effective diversity effect that is not affected by the distance between the transmitting antennas and the multiuser environment without introducing delayed transmission.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of a wireless communication system according to an embodiment of the present invention. As shown in the figure, the wireless communication system is composed of a first communication device (transmitter) 100 mainly functioning as a transmitter and a second communication device (receiver) 200 mainly functioning as a receiver. . The first communication device 100 includes a control unit 110 that controls the entire device, a reception unit 120, a transmission unit 130, a data allocation unit 140, and three antennas ANT1, 2, and 3. The second communication device 200 includes a control unit 210 that controls the entire device, a transmission unit 220, a reception unit 230, an acquisition unit 240, a signal processing unit 250, a storage unit 260, and three antennas ANT4, 5, and 6. Have. Wireless communication using a communication frame is performed between the first communication device 100 and the second communication device 200.

  The data allocation unit 140 of the first communication device 100 is data to be transmitted (encoded information (information symbol), redundancy information, etc.) encoded by a convolutional code, a turbo code, or an LDPC code, and further subjected to multilevel modulation. Is divided into two packets (physical minimum packets) or more and assigned in the frequency axis direction and / or the time axis direction of the communication frame. The control unit 110 controls the data allocation unit 140 to change the allocation state of the data in the frequency axis direction and / or the time axis direction for each communication frame. The transmission unit 130 encodes and modulates two or more frames in succession and transmits a communication frame whose allocation state in the frequency axis direction and / or the time axis direction is changed via the antennas ANT1, 2, 3 To the communication device 200. Alternatively, two or more packets are duplicated and a plurality of frames are transmitted continuously.

  The second communication device 200 receives a series of a plurality of frames transmitted from the first communication device by the receiving unit 230. The acquisition unit 240 acquires an allocation state when data to be transmitted is allocated to the communication frame received by the reception unit 230 in the frequency axis direction and / or the time axis direction. The signal processing unit 250 processes the plurality of communication frames received by the reception unit 230 based on the allocation state acquired by the acquisition unit 240.

  The second communication device 200 further includes a storage unit 260 that stores, for example, buffered transmission / reception packets, frequency hopping patterns, reception quality information for each frequency of the received signal, and the like.

  FIG. 2 is a detailed block diagram of the transmission unit 130 of the first communication device 100. This example is configured as a MIMO (Multiple Input Multiple Output) multicarrier transmitter. As shown in the figure, the transmission unit 130 includes a transmission signal generation unit 131, an encoding unit 132, and an OFDM modulation unit 136 that are divided into three systems. In addition, the transmission unit 130 is connected to the antennas ANT1, 2, and 3. The transmission unit 130 further includes a packet division recording / allocation unit 134 and an antenna division unit 135 that process three systems by one. First, the transmission signal generation unit 131 generates a signal from the original information (content etc.). The generated signal is convolved by the encoding unit 132 and encoded by turbo, LDPC, or the like. The adaptive modulation unit 133 adaptively modulates (QPSK, 64QAM, etc.) the encoded signal based on the reception quality notified from the receiver. The packet division recording / allocation unit 134 packet-divides the signal modulated by the adaptive modulation unit 133, allocates packets to the number of logical layers adapted to the reception quality (in this example, 3), and allocates packets allocated in subsequent frames. Hold (buffer). The antenna division unit 135 assigns the logical signal assigned by the packet division recording / assignment unit 134 to each of the transmission antennas ANT1, 2, and 3. An OFDM (Orthogonal Frequency Division Multiplexing) modulation unit 136 performs IFFT and guard interval insertion, performs OFDM modulation, and transmits a transmission signal to each of the antennas ANT1, 2, and 3.

In the example described above, the number of transmission signal trains has been described with an example of three systems, three layers, and three antennas. However, the present invention is not limited to this. For example, if the number of transmission signal sequences is L, the number of layers is M, and the number of antennas is N, these variables can be arbitrarily set under the following conditions.
L ≦ M ≦ N

  FIG. 3 is a detailed block diagram of the receiving unit 230 of the second communication device 200. This example is also configured as a MIMO (Multiple Input Multiple Output) multicarrier receiver. As shown in the figure, the receiving unit 230 includes an OFDM demodulating unit 231 divided into three systems. The receiving unit 230 is connected to the antennas ANT4, 5, and 6. The reception unit 230 further includes a channel estimation equalization unit 232 that processes three systems by one, and a packet recording / combination unit 233. The receiving unit 230 further includes an adaptive demodulation unit 234 and a decoding unit 235. The OFDM demodulator 231 performs OFDM demodulation by performing guard interval removal and FFT on the received signal received from each antenna. The channel estimation equalization unit 232 performs equalization processing by estimating the channel of the received signal from each antenna. The packet recording / synthesizing unit 233 records a signal composed of a plurality of layers in a plurality of frames, and also performs synthesis when synthesis is necessary. The adaptive demodulator 234 adaptively demodulates the modulated signal. The decoding unit 235 decodes the received signal.

In the above-described example, the number of received signal trains has been described with an example of three systems, three layers, and three antennas, but is not limited thereto. For example, if the number of layers is K and the number of antennas is J, these variables can be set arbitrarily under the following conditions.
K ≦ J

  FIG. 4 is a flowchart illustrating the processing of the transmitter according to one embodiment of the present invention. As shown in the figure, in step S11, a code / modulation process is performed on the original information to be transmitted. In step S12, the encoded and modulated data is allocated in the frequency axis direction and / or the time axis direction of the communication frame. In step S13, the allocation state of the data in the frequency axis direction and / or the time axis direction is changed for each communication frame. In step S14, the signal (communication frame) that has been subjected to the code / modulation processing and whose allocation state in the frequency axis direction and / or the time axis direction is changed is buffered. In step S15, the buffered signals are sequentially transmitted.

  FIG. 5 is a flowchart illustrating the processing of the receiver according to an embodiment of the present invention. As shown in the figure, in step S21, a signal (communication frame) transmitted from the transmitter is received. In step S22, the received signal is buffered. In step S23, the allocation state of the received signal in the frequency axis direction and / or the time axis direction is acquired. The allocation state may be acquired from some signal superimposed on the received signal, or the allocation pattern may be notified in advance from the transmitter, stored in the storage unit 260, and read at the time of reception. . Next, in step S24, the received signal is demodulated and decoded.

  FIG. 6 is a diagram for explaining 3-packet block hopping transmission / reception using OFDM modulation according to an embodiment of the present invention. In this example, the allocation state is changed in the frequency axis direction. One block is composed of 6 OFDM symbols with 8 subcarriers. As shown in the figure, data is transmitted by hopping to another block (different frequency) for each frame in three frames. This makes it possible to suppress fading correlation in terms of time and frequency. For example, it is possible to set the coding rate to 3 by turbo coding, information symbols in the first packet, first parity symbols in the second packet, and second parity symbols in the third packet. Frame 1 of the first packet is transmitted at the frequency of block BL1, frame 2 of the second packet is transmitted at the frequency of another block BL2, and frame 3 of the third packet is transmitted at the frequency of yet another block BL3. Sent.

  As shown in FIG. 6, the frequency is changed between frames 1 and 2 by hopping (randomizing) with PN code or the like in units of OFDM subcarriers or subchannels. The same processing is performed for frame 2 and subsequent frames. Multi-users hop similarly. If the allocation state is changed in the frequency axis direction for each frame in this way, error tolerance is further improved.

  FIG. 7 is a diagram illustrating 2-packet subcarrier hopping transmission / reception using OFDM modulation according to an embodiment of the present invention. This example also changes the allocation state in the frequency axis direction. As shown in the figure, each packet is transmitted by subcarrier hopping (frequency interleaving) within each frame. This makes it possible to suppress fading correlation in terms of time and frequency. In this case, since the frequency is hopped in units of subcarriers, the configuration is particularly resistant to burst errors in a certain frequency band.

  FIG. 8 is a diagram illustrating two-packet identical packet transmission / reception using OFDM modulation according to an embodiment of the present invention. In this example, the allocation state is changed in the frequency axis direction and the time axis direction. That is, the same packet is duplicated and assigned to two frames. One block is composed of 6 OFDM symbols with 8 subcarriers. As shown in the figure, the same packet is transmitted with frequency hopping continuously for two frames. Accordingly, the receiver obtains the time diversity gain and the frequency diversity gain by receiving the frame 1 and the frame 2.

  FIG. 9 is a diagram illustrating transmission / reception of two-packet MIMO2 multiplexing using OFDM modulation and MIMO multiplexing according to an embodiment of the present invention. In this example, the allocation state is changed in the frequency axis direction. One block is composed of 6 OFDM symbols with 8 subcarriers. As shown in the figure, a sequence 1 packet PKT11 and a sequence 2 packet PKT21 are transmitted at the timing of frame 1 in a block BL1 of the same frequency band. The series 1 packet PKT12 and the series 2 packet PKT22 are transmitted at the timing of frame 2 in the block BL2 in the same frequency band. That is, two series of packets are transmitted by frequency hopping for two consecutive frames. Accordingly, the receiver obtains the time diversity gain and the frequency diversity gain by receiving the frame 1 and the frame 2. For example, when the coding rate is 2 by turbo code, the packet PKT11 of the series 1 may be an information symbol and the packet PKT12 may be a parity symbol.

  FIG. 10 is a diagram illustrating transmission / reception of two-packet MIMO-2SDMA using OFDM modulation, MIMO multiplexing, and space division multiplexing (SDMA) according to an embodiment of the present invention. In this example, the allocation state is changed in the frequency axis direction. One block is composed of 6 OFDM symbols with 8 subcarriers. As shown in the figure, a sequence 1 packet PKT11 and a sequence 2 packet PKT21 are transmitted at the timing of frame 1 in block BL1 of the same frequency band. The series 1 packet PKT12 and the series 2 packet PKT22 are transmitted at the timing of frame 2 in the block BL2 in the same frequency band. That is, two series of packets are transmitted by frequency hopping for two consecutive frames. Note that in this example, the receiver is two separate devices. Accordingly, the receivers 1 and 2 (users 1 and 2) receive the frame 1 and the frame 2 to obtain the time diversity gain and the frequency diversity gain. For example, when the coding rate is 2 by turbo code, the packet PKT11 of the series 1 may be an information symbol and the packet PKT12 may be a parity symbol.

  The configuration and processing of the embodiment of the present invention will be described again. A transmission signal encoded by a convolutional code, a turbo code, or an LDPC code and subjected to multilevel modulation is buffered for two packets (physical minimum packet) or more, and continuously transmitted for two or more frames. Alternatively, it is possible to duplicate two packets and repeatedly transmit a plurality of frames to obtain a gain repeatedly. In the MIMO multiplex transmission, for example, the communication path can be switched by transmitting from the first layer in the first frame and transmitting from the second layer in the second frame in two multiplexes. In the case of transmission of two or more packets, the turbo code transmits an information signal in the first frame and a parity redundancy code in the second and subsequent frames. Alternatively, interleave and transmit. According to the embodiment of the present invention, even with a convolutional code, it is possible to transmit the same by sequentially dividing the first frame from the first frame or by interleaving. The receiver can acquire control information such as an allocation state from previous information such as a control channel with the transmitter, and performs the above-described reception-side processing based on this information. It is also possible to buffer received signals of two or more frames and perform adaptive demodulation and error correction decoding processing.

  The advantages of the present invention will now be described again. Since this technique suppresses fading correlation in the time direction and the frequency direction, it does not depend on the physical interval between the transmitting antenna and the receiving antenna. Since a plurality of transmitting antennas do not perform delayed transmission, there is no influence of interference due to delay during reception. By performing frequency hopping and not performing delayed transmission, it is possible for multi-users to reduce the fading correlation while suppressing the occurrence of interference.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each unit, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined or divided into one. It is.

It is a block diagram of the radio | wireless communications system by the embodiment of this invention. 3 is a detailed block diagram of a transmission unit 130. FIG. 3 is a detailed block diagram of a receiving unit 230. FIG. It is a flowchart explaining the process of the transmitter by one embodiment of this invention. It is a flowchart explaining the process of the receiver by one embodiment of this invention. FIG. 6 is a diagram for explaining 3-packet block hopping transmission / reception using OFDM modulation according to an embodiment of the present invention. It is a figure explaining 2 packet subcarrier hopping transmission / reception using OFDM modulation by one embodiment of the present invention. It is a figure explaining 2 packet same packet transmission / reception using OFDM modulation by one embodiment of the present invention. It is a figure explaining transmission and reception of 2 packet MIMO2 multiplexing using OFDM modulation and MIMO multiplexing according to an embodiment of the present invention. It is a figure explaining transmission and reception of 2 packet MIMO-2SDMA using OFDM modulation, MIMO multiplexing, and space division multiplexing (SDMA) according to an embodiment of the present invention.

Explanation of symbols

100 first communication device 110 control unit 120 reception unit 130 transmission unit 131 transmission signal generation unit 132 encoding unit 133 adaptive modulation unit 134 packet division recording / allocation unit 135 antenna division unit 136 OFDM modulation unit 140 data allocation unit 200 second Communication device 210 control unit 220 transmission unit 230 reception unit 231 OFDM demodulation unit 232 channel estimation equalization unit 233 packet recording / combination unit 234 adaptive demodulation unit 235 decoding unit 240 acquisition unit 250 signal processing unit 260 storage unit ANT1-6 antenna BL1 -3 blocks PKT11, 12, 21, 22 packets

Claims (9)

A communication device that communicates between another device and its own device using a communication frame having a frequency axis and a time axis,
A data allocation unit that allocates data to be transmitted to the communication frame;
A control unit that controls the data allocation unit to change the allocation state of the data in the frequency axis direction and / or the time axis direction for each of the communication frames;
A transmission unit for transmitting a plurality of communication frames whose allocation state has been changed to the other communication device;
A communication apparatus comprising: The communication device according to claim 1,
The control unit is
Controlling the data allocation unit to change the allocation state of the data to be transmitted in the frequency axis direction for each communication frame;
A communication device. The communication device according to claim 1,
The control unit is
Controlling the data allocation unit to change the allocation state of the data to be transmitted in the frequency axis direction and the time axis direction for each communication frame;
A communication device. The communication apparatus according to any one of claims 1 to 3,
The assigning unit
Assign the same data to be transmitted to multiple communication frames,
A communication device. The communication apparatus according to any one of claims 1 to 3,
The communication frame is OFDM-modulated and MIMO multiplexed.
A communication device. The communication apparatus according to any one of claims 1 to 3,
The communication frame is OFDM modulated, MIMO multiplexed, and space division multiplexed.
A communication device. In the communication system which communicates using the communication frame which has a frequency axis and a time axis between the communication apparatus of any 1 paragraph of Claims 1-6, and other communication apparatuses,
The other communication device is
A receiving unit for receiving the plurality of communication frames transmitted from the communication device;
A signal processor that processes the plurality of communication frames received by the receiver based on the allocation state;
A communication system comprising: A communication device that communicates between another device and its own device using a communication frame having a frequency axis and a time axis,
A receiving unit that receives a plurality of communication frames transmitted from the other communication device and assigned data in the frequency axis direction and / or the time axis direction;
An acquisition unit that acquires an allocation state when the other communication device allocates data to be transmitted to the communication frame in the frequency axis direction and / or the time axis direction;
A signal processing unit that processes the plurality of communication frames received by the receiving unit based on the allocation state acquired by the acquiring unit;
A communication apparatus comprising: A communication control method in a communication device that communicates between another device and its own device using a communication frame having a frequency axis and a time axis,
A data allocation step for allocating data to be transmitted to the communication frame;
A control step for controlling the allocation state of the data in the frequency axis direction and / or the time axis direction for each of the communication frames;
A transmission step of transmitting a plurality of communication frames whose allocation state has been changed to the other communication device;
A communication control method characterized by comprising:

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